Matable connectors using one or more male and female contacts have been used widely for interconnecting electrical circuits in consumer electrical or electronic appliances, automobiles, etc. Typical and widely used male contacts are commonly referred to as tab contacts each having a relatively wide contact surface. On the other hand, typical and most widely used receptacle contacts have box-shaped contact sections as disclosed in Japanese UM laid-open No. 64 (1989)-38777. Advantages of this type of receptacle contact are relatively rugged in construction to well-protect the inner contact member from external stress. Such contacts are generally received and retained in contact receiving cavities in a connector housing by engaging a respective resilient arm formed in each contact receiving cavity with the box-shaped contact section at the rear end thereof.
For more reliable retention of the receptacle contacts in the connector housing, a double-lock member is employed to be mounted on the connector housing for engaging with other parts of such receptacle contacts. In this way, each receptacle contact is reliably retained in the connector housing by both the resilient arm in each contact receiving cavity, and the double-lock member in such particular applications as automobiles subjected to strong vibration and shock.
When the receptacle contact is being inserted into the contact receiving cavity in the housing, the resilient arm is slid over the upper surface of the box-shaped contact section of the receptacle contact by being deflected against the resiliency of the resilient arm. The box-shaped contact section of the receptacle contact needs to have a certain length to maintain effective contact length with the matable male contact. While the resilient arm contacts the upper surface of the contact section, the receptacle contact is subjected to pressure by the resilient arm. The frictional force by the pressure acts as the insertion force of the contact section. It is, therefore, possible that the operator would stop inserting the contact before the resilient arm reaches the rear end of the contact section.
Also, the receptacle contact as disclosed in the above mentioned UM specification has a very limited area to effectively abut against the resilient arm when the resilient arm engages the contact section at the rear end thereof because the upper wall or surface of the contact section is made of a single sheet of metal plate. As a result, when a pulling force is applied to the contact, the resilient arm is often sheared or broken by the relatively sharp edge at the rear end of the contact section.
It is therefore an object of the present invention to provide a receptacle contact free from the above problem, and to provide a connector for using such a contact or contacts; that is, to provide such a contact with improved loading resistance and to prevent damage of the resilient arm in the housing.
Additionally, electrical connectors for certain applications, e.g., automobiles and the like, require enhanced or more reliable resistance to a tensile force applied to the contacts, thereby utilizing a double-lock member to provide additional retention force to the contacts. Such a double-lock member is conveniently mounted on the housing after the contacts have been loaded in the respective contact receiving cavities in the housing. However, there is an instance where the double-lock member must be removed for replacing any defective contact or repositioning the contacts once loaded in the cavities.
It is therefore an additional object of the present invention to provide a double-lock connector in which the double-lock member can be easily removed, if required, by using a simple tool, e.g., a screw driver or the like.